This invention relates to four-cycle internal combustion engines.
The admission stroke and the explosion stroke of conventional four-cycle internal combustion engines are the same, due to the construction of the engines, and at the end of the explosion stroke, the engines exhaust combusion gases, which still have considerable energy of compression, as exhaust gases to the atomosphere.
An object of the present invetion is to provide a four-cycle internal combustion engine the explosion stroke of which is longer than the admission stroke.
Another object of the invention is to provide a four-cycle internal combustion engine capable of utilizing compression energy of exhaust gases so that the efficiency of the engine may be increased, while cleaning exhaust gases.
To accomplish these purposes, this invention provides a four-cycle internal combustion engine having a piston 70 reciprocably movable within a cylinder 80, a crankshaft 10, a rod 60 connecting the piston 70 to the crankshaft 10 and means arranged between the rod 60 and the crankshaft 10 to vary the stroke of the piston 70, said means for varying the stroke comprising an internal gear 20 fixed on the frame 90 of the engine, an external gear 30 engaged with the internal gear 20 as rotatably supported on the crankpin 12 of the crankshaft 10 an eccentric member fixed eccentrically to the crankpin 12 on the external gear 30, characterized in that the eccentric distance of the crankpin 12, the radius of the pitch circle of the external gear 30 and the radius of the pitch circle of the internal gear 20 are in the ratio of one to two to three.